Experiments on dough rheology to improve screening of bread wheat cultivars

The bread‐making potential of flour may be roughly estimated by dough rheology, especially its tolerance to over‐mixing as determined with the farinograph. The objective of this study was to identify the relative effects of experimental conditions likely to affect dough mixing stability: mixer speed, temperature, salt, yeast and bread additives such as ascorbic acid and preservatives. The addition of 1–2% salt or ascorbic acid (50 mg kg^?1 flour) improved dough mixing stability and counteracted the negative effect of bread preservatives. Mixing salted dough at slow speed (63 rpm) and 25 °C might be a more realistic bread‐making procedure for performing dough rheology assays with equipment such as the farinograph, compared to official methods (only flour and water, no salt; 30 °C). Amongst five bread wheat cultivars, differences existed in dough strengthening response to both salt and ascorbic acid, a property that may find application in wheat breeding and screening.     

Effect of xanthan gum on processing and cooking quality of nontraditional pasta

The physicochemical properties of three different commercial sources of xanthan gum (XG) were determined, and its subsequent effect on the processing and cooking quality of pasta containing nontraditional ingredients was characterised. Commercial durum flour was fortified with nontraditional ingredients (soya flour or oat flour, 10% w/w) and XG (2% w/w). Protein content, ash content, bulk density, water‐holding capacity and total glucose content significantly varied among XG samples from different vendors. Xanthan gum increased dough strength of durum flour and the extent of strengthening varied with vendor of XG. For example, time‐to‐peak ranged from 2.75 to 4.25 min; peak width from 2.5 to 3.75 BU; and end width from 2 to 3 BU depending on the vendor of XG. Processing properties differed depending on commercial source. Commercial XG that had the finest particle size required the lowest mechanical energy (range 253–270 J s^?1) and had the greatest extrusion rate (range 3.38–3.65 g s^?1), both of which resulted in the lowest specific mechanical energy (range 69–79 J g^?1) required to extrude spaghetti samples.     

The antioxidant activity and the composition of free and bound phenolic acids in dough of wheat flour enriched by Boletus edulis after mixing and thermal processing

The porcino is good source of phenolics and has been used to enrich wheat flour. The antioxidant activity and the content and composition of free and bound phenolic acids in the dough of wheat and porcino flour mixture (70:30 w/w) were investigated. The free form in the amount of 1305.76 μg g^?1 was the main part of the phenolic content in the flour mixture. By dough mixing, the content of free phenolics increased by approximately 70%. Further thermal processing decreased the content of both forms of phenolics compared to dough after mixing, but the content of free phenolics of 1764.24 μg g^?1 is still higher than in the flour mixture. The stability of the detected phenolic acids during mixing and thermal processing depended on whether they were in free or bound form. After thermal processing, the total content of detected phenolic acids was 683.31 μg g^?1, indicating that approximately 87% of the total content of phenolic acids detected in flour mixture was retained.     

Separation of bread wheat flours into starch and gluten fractions: effect of water temperature alone or in combination with water to flour ratio

Two different commercial bread wheat flours (BF‐I, 65% extraction and BF‐V, 86% extraction) were separated into gluten and starch milk by making a dough, allowing some time for maturation, dispersing the dough in water and wet sieving/washing. The effect of using of warm water (20–45 °C) for dough making and washing on separation was studied for BF‐I flour at 640 g kg^?1 water to flour ratio of and 300 s maturation time, and the separation was found to improve with increase in temperature. The combined effects of water temperature (20–50 °C) and water to flour ratio (640–780 g kg^?1 for BF‐I and 620–870 g kg^?1 for BF‐V) were studied at 600 s maturation time. The quantities and dry matter contents of the gluten fraction and starch milk were measured; a sample of starch milk was centrifuged to obtain decantate, tailing and prime starch fractions, and the dry matter contents of each were determined. All the dried samples were also analysed for protein content, and the fractional recoveries of dry matter and protein in the gluten fraction, prime starch, tailings and decantate were calculated. The results indicated the optimum point for BF‐I flour to be the combination of optimum farinograph water absorption and 40 °C. BF‐V showed very poor separation behaviour within the ranges studied. At the optimum farinograph water absorption the use of warm water for dough making and 20 °C water for washing steps was also tried, but no significant improvement over the 20 °C results was obtained. © 2002 Society of Chemical Industry     

The advantage of using extrusion processing for increasing dietary fibre level in gluten-free products

Gluten-free products generally are not enriched/fortified and frequently are made from refined flour and/or starch. Such products have been found to provide lower amounts of total dietary fibre than their enriched/fortified gluten-containing counterparts.The objective of this study was to increase the level of total dietary fibre in gluten-free products by using extrusion technology and by incorporating a number of different fruits and vegetables, such as apple, beetroot, carrot, cranberry and gluten-free Teff flour cereal. The materials were added at the level of 30% into the gluten-free balanced formulation (control) made from rice flour, potato starch, corn starch, milk powder and soya flour. Different process conditions, such as water feed rate 12%, solid feed rate 15–25 kg/h, screw speed 200–350 rpm, barrel temperatures: 80 °C at feed entry and 80–150 °C at die exit were used. Pressure, material temperature and torque were monitored during extrusion runs. The relationships and interactions between raw ingredients, extrusion processing parameters and resulting extrudate nutritional and textural properties were investigated.The results of this study clearly show that extrusion technology has the potential to increase the levels of total dietary fibre in gluten-free products made from vegetables, fruits and gluten-free cereals.     

马铃薯全粉剂量效应对面团特性以及馒头品质作用分析

为丰富馒头营养和品种,向面团中加入马铃薯全粉,分析马铃薯全粉基本成分及物化特性,探究马铃薯全粉剂量效应对混粉、面团特性,以及馒头品质影响的研究。结果表明,马铃薯全粉中主要成分为淀粉,含量约为67.07%;马铃薯全粉的持水性、吸水膨胀性分别为3.57 g/g、2.49 mL/g;马铃薯全粉的粘度为12.71 m2/s,与面粉混合可以增强面团的物化特性。马铃薯全粉的添加使得面团粉质特性变差,揉混特性变好,添加量为8%~15%时,面团糊化特性和拉伸特性较好;随着马铃薯全粉添加量的增加,马铃薯馒头表皮、内瓤白度降低;马铃薯全粉添加量为5%~8%时,馒头比容、硬度、胶着性和咀嚼性较大,感官评分高。综上所述,为提高面团特性,马铃薯全粉的建议添加量为8%~15%;为改善馒头品质,马铃薯全粉的建议添加量为5%~8%。     

Heating Conditions and Bread-Making Potential of Substandard Flour

ABSTRACT Heating weak bread flours (commercial cookie flour; commercial stone‐milled bread flour; Fundulea, a weak bread cultivar) at 80°C for 15 min had a positive effect on bread volume (P < 0.05). This positive effect was best seen when ascorbic acid was removed from bread formulation. Crumb springiness and fineness of grain, but not crumb hardness, were significantly improved after flour heating; cohesiveness improved with heated cookie flour (P < 0.05). After heating, flour a‐amylase content was lower; dough‐mixing stability of cookie flour doubled to 7.1 min but dropped from 18.0 to 4.8 min with standard bread flour. Heating offers possibility to upgrade substandard flour for bread‐making applications, especially in oxidant‐free dough system.     

Effect of butter content and baking condition on characteristics of the gluten‐free dough and bread

This study aimed to investigate effect of butter content (0–30 g/100 g flour) and baking conditions hot air baking (HA), microwave baking (MW) and hot air‐microwave baking (HA‐MW) on quality of the rice flour dough and bread. The increased butter (up to 15 g butter/100 g flour) enhanced elastic modulus (G′) and viscous modulus (G″) of dough and specific volume of bread. Additionally, the increased butter improved crust colour and reduced hardness of the bread. The HA‐MW and MW conditions were useful for the gluten‐free bread by reducing baking time and predicted glycemic index (GI), regardless of butter content. However, enthalpy of retrogradation and crystallinity in the HA‐MW and MW bread stored at 4 °C for 7 days were increased and higher than those of the HA bread, indicating a faster staling. The predicted GI of both MW and HA‐MW bread remained at a medium level during storage.     

Bread fortified with dietary fibre extracted from culinary banana bract: its quality attributes and in vitro starch digestibility

The effect of fortification of dietary fibre (DF) on dough rheology, quality characteristics and in vitro starch digestibility of bread was studied. Bread was prepared incorporating DF (2–4 g per 100 g of flour mixture). Rheological study of dough showed an increase in dough stiffness and elasticity with higher incorporation of the DF. The results of chemical composition revealed that addition of DF increased total DF (19.65 g per 100 g) content of bread. However, incorporation of 2 g per 100 g DF of flour mixture with 66 g per 100 g moisture showed higher water retention and specific volume of 86.76% and 5.83 cm³ g⁻¹, respectively, which was close to control bread. Improved textural property with acceptable sensory attributes was observed for bread fortified with 2 g per 100 g DF of flour mixture and 66 g per 100 g moisture content. Incorporation of DF (2–4 g per 100 g of flour mixture) showed a decrease in rapidly digestible starch (RDS) and an increase in slowly digestible starch (SDS) content with lower predicted glycaemic index (pGI) than control bread.     

甘薯生全粉对面团特性及馒头品质的影响

该实验以甘薯-小麦混粉为原料,探究甘薯生全粉添加量对混粉特性、混粉面团特性以及甘薯生全粉馒头综合品质影响的研究。结果表明,甘薯生全粉中主要成分为淀粉,含量约为64.60%;随着混粉中甘薯生全粉含量的增加,混粉的持水性从1.16 g/g增加至1.70 g/g,持油性呈先增大后减小的变化趋势。随着甘薯生全粉添加量增大,混粉粉质特性变差,面团加工品质降低;随着混粉面团中甘薯生全粉含量的增加,面团的TO、TP、TC、硬度逐渐增大,弹性逐渐减小;甘薯生全粉添加量在20%以内时,甘薯馒头感官评分大于70,馒头的质构、比容和白度仍在可接受范围内。综上所述,当甘薯生全粉添加量小于10%时,混合面团的加工特性和馒头品质较优;当甘薯生全粉添加量小于20wt%时,混合面团的加工特性和馒头品质在可接受范围内。     

Effect of high hydrostatic pressure to sweet potato flour on dough properties and characteristics of sweet potato‐wheat bread

The effect of high hydrostatic pressure (HHP, 100–400 MPa) for 20 min at 25 °C to sweet potato flour (SPF) on dough properties and characteristics of sweet potato‐wheat bread was investigated. The particle size of SPF after HHP was decreased significantly. The obvious rupture was observed in granules of SPF after HHP at 300 and 400 MPa by scanning electron microscopy (SEM). After HHP, significant differences on endothermic peak temperatures (T_P) of SPF were observed by differential scanning calorimetric (DSC), of which the enthalpy change (ΔH) had a slight increase, expect that at 200 MPa. Gas retention of dough with SPF after HHP increased markedly from 1199 (0.1 MPa) to 1246 ml (100 MPa). Specific loaf volume of bread with SPF at 400 MPa was increased significantly, while the hardness and chewiness were reduced. Thus, SPF treated with HHP at 400 MPa could be potentially used in wheat bread production.     

Significance of healthy viscous dietary fibres on the performance of gluten‐free rice‐based formulated breads

The impact of associated viscous dietary fibres (hydroxypropylmethylcellulose semi‐firm – SFE‐ and weak – NE‐gel forming, and barley ß‐glucan, BBG) incorporated at different amounts (1.6–7.5%, flour basis) into gluten‐free rice‐based dough formulations on the breadmaking performance and staling behaviour of hydrated (70–110%, flour basis) fibre‐flour composite blends has been investigated. Single BBG addition fails to mimic gluten visco‐elasticity properly, but simultaneous incorporation of either SFE or NE contributes to bread improvement in terms of bigger volume and smoother crumb. 3.3 g of BBG (70% purity) and 104 mL of water addition to 100 g rice flour provided sensorially accepted breads (7.6/10) with a theoretical ß‐glucan content of 1.24 g per 100 g GF bread that would allow a daily ß‐glucan intake of 3 g provided a bread consumption of 240 g day^?1. Complementary tests should be carried out to know the amount and molecular weight of ß‐glucan in the final bread before assuring the nutritional benefit of this addition.     

Effect of native and germinated finger millet flour on rheological and sensory characteristics of biscuits

Wheat flour was replaced with native finger millet flour (NFMF) and germinated finger millet flour (GFMF) at 30–50% levels to make soft dough biscuits. Dough rheological properties and baking characteristics of the blends were evaluated. Farinograph data of wheat flour replaced with NFMF and GFMF showed a decrease in water absorption, dough stability and an increase in mixing tolerance index as the level of replacement increased. Extensibility of dough decreased for both NFMF and GFMF as the levels increased. The hardness of biscuit dough measured by texture profile analysis increased from 125 to 234 N for NFMF and 118 to 126 N for GFMF. Scanning electron microscopic studies on the biscuit dough showed polygonal finger millet starch granules adhering to wheat starch granules and protein matrix. The results of the study indicated that the replacement level of 40% with either NFMF or GFMF produced biscuits with acceptable sensory attributes. Addition of sodium stearoyl‐2‐lactylate (SSL) showed further improvement in terms of spread ratio, surface characteristics and texture.     

Effect of β-Glucan Concentrate on the Water Uptake,Rheological and Textural Properties of Wheat Flour Dough

The effects of the addition of β-glucan concentrate (2.5–10 g/100 g flour) and water (58–70 mL/100 g flour) on the rheological and textural properties of wheat flour doughs were studied. Various empirical (farinograph, extensograph, dough inflation, and dough stickiness) and fundamental rheological tests (oscillatory and creep-recovery) were employed to investigate composite dough structure and an attempt was made to correlate the data obtained from different instrumental measurements. The water absorption increased with the addition of β-glucan concentrate into wheat flour. An increase in mixing time and stability were recorded upon addition of β-glucan concentrate (≤ 5 g/100 g flour), and the extensibility decreased at similar condition. The composite dough exhibited predominating solid-like behavior. The mechanical strength, dough stickiness, the peak dough inflation pressure decreased with increasing water content but those parameters increased with β-glucan concentrate incorporation within the studied concentration range. Creep-recovery tests for 5 g β-glucan concentrate/100 g flour doughs recorded less resistance to deformation with an increase in water level and data were well described by the Burger model. Thermal scanning of doughs revealed that the protein denaturation peak was significantly influenced by water content, and the values were ranged between 110 and 124°C. Significant relationships between empirical and fundamental rheological testing methods were found.     

Compositional and varietal influence of finger millet flour on rheological properties of dough and quality of biscuit

Biscuits prepared from flour composites containing 60:40 and 70:30 (w/w) finger millet:wheat flour were evaluated for its dough characteristics and biscuit quality. Hardness of biscuit dough measured by textural profile analysis was more in 60:40 combination than in 70:30 level. The dough became more adhesive with higher level of wheat flour and it varied across varieties. Extensograph data also showed that resistance of biscuit dough increased with the increasing levels of wheat flour. However, very little difference was observed between addition of 30 and 40 g/100 g wheat flour in terms of resistance to extension. Wheat composite flour (40 g/100 g) had higher water absorption capacity than in 30 g/100 g composite flour. Bandwidth of composite flour was narrower in 40 g/100 g wheat flour composite. Expansion of biscuit and breaking strength after baking was more in 70:30 composite than in 60:40. Among the varieties used, VL-324 brought about the positive changes of composite flour in rheological characteristics in terms of adhesiveness, extensibility and resistance to extension, which in turn improves biscuit quality. It provided better physical quality biscuit dough and biscuit in terms of its spread ratio, density and breaking strength. Studies indicated that composite of finger millet and wheat flour (60:40) was found better, particularly in case of biscuit quality. Out of six varieties, VL-324 was found best in terms of biscuit quality as well as acceptability.     

Functional properties of tortillas with triticale flour as a partial substitute of nixtamalized corn flour

The effect of partial substitution of nixtamalized corn flour for triticale flour in functional properties of dough and tortillas was evaluated. Seven blends of refined triticale and nixtamalized corn flour (NCF) were tested in a traditional process of tortilla production. Triticale flour significantly reduced water absorption of dough, tortillas cooking time and yield. NCF-Triticale flour blends for making tortillas using water to 80 °C improves the consistency and cohesiveness of dough. A mix containing more than 25 g of triticale flour per 100 g of flour develop inadequate adhesiveness of the dough, which is inconvenient when using the manual press. The extensibility of tortilla blends was lower than pure NCF tortillas. The advisable proportion for triticale flour used as a partial substitute of nixtamalized corn flour was 100 g kg⁻¹ (flavor, color, texture and an acceptable adhesiveness).     

Rheological Characterisation of Malaysian Varieties of Sweet Potato Doughs Using Large and Small Deformation Measurements

The rheological properties of sweet potato doughs at different mixing times were studied. In the large deformation extension test, extensibility parameters including dough length at fracture, measured, and actual forces acting on dough strips were obtained for calculating the stress-strain data. For the small deformation test, both storage and loss modulus of dough were studied. The extensibility of dough from sweet potato flour increased to its peak at five minutes mixing time before decreasing illustrating an optimum mixing time. The variety of VitAto which has a higher protein content of 5.7 g/100 g has higher values of all the extensibility parameters as compared to Bukit Naga and Okinawan. In terms of flow-behavior index, all sweet potato doughs displayed n values from 1.82 to 2.11, indicating strain hardening behaviors similar to wheat flour doughs. The small deformation tests were not able to identify the optimum mixing time, although in general, illustrated that sweet potato doughs were essentially elastic or recoverable. The Pearson correlations of large and small deformation tests showed that the rheological parameters were positively correlated among themselves in the evaluation of the effect of mixing time to rheological properties of sweet potato dough.     

Potato flour as a functional ingredient in bread: evaluation of bread quality and starch characteristics

Potatoes have been added to bread for improvement of texture and moisture retention. The functional quality and starch digestibility in bread containing 5%, 10% or 15% potato flour were evaluated. Farinograph absorption of wheat and potato flour blends ranged from 59.0% to 77.7%. Bread with potato flour had significantly (P < 0.05) lower bread firmness during storage. There was a significant (P < 0.05) decrease in starch molecular weight as the level of potato flour increased. Inclusion of potato flour in these breads significantly (P < 0.05) increased the level of resistant starch (RS), while significantly (P < 0.05) decreasing the estimated glycemic index (eGI). Bread with no potato flour had 5.2% RS and an eGI of 95, while the bread with 15% potato flour had 11.3% RS and an eGI of 87. Overall, the addition of potato flour may reduce dough strength and loaf volume, but it reduced staling and increased resistant starch content of the bread.     

Effects of hydrothermal processing on rutin retention and physicochemical properties of Tartary buckwheat enriched dough and Chinese steamed bread

Effects of hydrothermal processing on content changes of rutin, quercetin and total flavonoids and physicochemical properties of Tartary buckwheat (TB) enriched dough and Chinese steamed bread (CSB) were investigated. Rutin loss and bitterness in CSB made from mixed wheat flour and hydrothermally processed TB flour decreased markedly compared with control. Total flavonoids were increased in dough after fermentation but decreased afterwards in CSB significantly (P < 0.05). The development time, stability time, extensibility, storage and loss moduli and tan δ of TB enriched dough, along with the volume, textural properties, sensory evaluation and bitterness of derived CSB, were significantly affected by hydrothermal processing temperature and time. Hydrothermal processing of TB flour at 100 °C for 20 min, compared with 100 °C for 10 min, 30 min or 121 °C for 10 min, 20 min, 30 min, was suggested to be a relatively better pretreatment condition for the present TB enriched CSB.     

Effect of moderate hydrothermal-acidic modified potato pulp on the rheological properties of wheat dough

This study aimed to investigate the potential of moderate hydrothermal (50–80 °C) and acidic (0%–0.35% citric acid) modification of potato pulp (PP) to improve the rheological properties of wheat dough. The results show that hydrothermal treatment (HMT) and citric acid (CA) decreased the swelling power, thickening ability and gelatinisation enthalpy, as well as increased the solubility and gelatinisation temperature, of PP with an increase in temperature and CA addition. Additionally, HMT- (80 °C) and CA- (0.07%–0.35%) modified PP effectively enhanced dough strength against mixing and suppressed retrogradation. The thermochemical parameters of the composite dough were significantly correlated with the swelling power, rapid visco analyser (RVA) viscosity parameters (except setback viscosity) and differential scanning calorimetry (DSC) parameters (P < 0.05). The results suggest that moderate hydrothermal-acidic treatment is an effective way to overcome dough mixing and retrogradation shortages in potato pulp-based staple production.